Flaskを実行すると "WinError 10038"が返されます

Question

単純なFlaskアプリを実行すると、OSError: [WinError 10038] An operation was attempted on something that is not a socketが発生します。ページはブラウザに表示されません。エラーはどういう意味ですか？どうすれば修正できますか？

from flask import Flask, render_template 

app = Flask(__name__) 

@app.route('/') 
def index(): 
    return 'Hello, World!' 

if __name__ == '__main__': 
    app.run(debug=True) 

* Running on http://127.0.0.1:5000/ (Press CTRL+C to quit) 
* Restarting with stat 
* Debugger is active! 
* Debugger pin code: 294-294-951 
Exception in thread Thread-1: 
Traceback (most recent call last): 
    File "C:\Users\kdalal\AppData\Local\Continuum\Anaconda3\lib\threading.py", line 916, in _bootstrap_inner 
    self.run() 
    File "C:\Users\kdalal\AppData\Local\Continuum\Anaconda3\lib\threading.py", line 864, in run 
    self._target(*self._args, **self._kwargs) 
    File "C:\Users\kdalal\AppData\Local\Continuum\Anaconda3\lib\site-packages\werkzeug\serving.py", line 670, in inner 
    fd=fd) 
    File "C:\Users\kdalal\AppData\Local\Continuum\Anaconda3\lib\site-packages\werkzeug\serving.py", line 564, in make_server 
    passthrough_errors, ssl_context, fd=fd) 
    File "C:\Users\kdalal\AppData\Local\Continuum\Anaconda3\lib\site-packages\werkzeug\serving.py", line 474, in __init__ 
    socket.SOCK_STREAM) 
    File "C:\Users\kdalal\AppData\Local\Continuum\Anaconda3\lib\socket.py", line 460, in fromfd 
    nfd = dup(fd) 
OSError: [WinError 10038] An operation was attempted on something that is not a socket 

Answer 1

このissueはWERKZEUG 0.12.1でfixedました。最新バージョンにアップグレード：

pip install -U werkzeug